Exchange Of Materials Flashcards
What is the equation for photosynthesis?
Carbon dioxide + water → glucose + oxygen. Light energy, absorbed by chlorophyll, is needed for photosynthesis to happen.
Which gas is released when plant cells respire aerobically?
Aerobic respiration produces carbon dioxide gas.
When does respiration happen in plants?
Respiration happens all the time in plants. It is photosynthesis that does not happen in the dark, for example during the night.
How do plants obtain the carbon dioxide they need for photosynthesis?
Plants obtain the carbon dioxide they need for photosynthesis by diffusion from the air. Active transport is not needed and would use energy.
Which of these is an adaptation of leaves for efficient gas exchange?
The stomata, tiny pores in the lower epidermis, are an adaptation for gas exchange in leaves. The waxy cuticle helps to protect the leaf from drying out.
What happens to stomata in the light?
In the light, guard cells absorb water by osmosis and become turgid rather than flaccid. This lets them open. The stomata do close when the guard cells are flaccid due to loss of water.
When is the movement of carbon dioxide, oxygen and water vapour at the surface of the leaf likely to be greatest?
The movement of carbon dioxide, oxygen and water vapour at the surface of the leaf is likely to be greatest when the stomata are open. Cool, humid conditions are likely to decrease the movement of water vapour.
What colour would hydrogencarbonate indicator be at high concentrations of carbon dioxide?
Hydrogencarbonate indicator would be yellow at high concentrations of carbon dioxide. It would be purple at low concentrations.
Net gas exchange from a leaf can be investigated using hydrogencarbonate indicator in a stoppered tube. Why might one of the test leaves be boiled first?
A boiled leaf acts as a control to show that a leaf has to be alive for it to affect the amount of carbon dioxide in the tube. Photosynthesis and respiration will not happen in a dead leaf, whatever the temperature.
